High pressure pump for sprayer



March 4, 1969 J. WAGNER 3,430,577

HIGH PRESSURE PUMP FOR SPRAYER Filed June 19, 1967 INVENTOR JOSEF WAGNER ATTORNEY United States Patent 3,430,577 HIGH PRESSURE PUMP FOR SPRAYER Josef Wagner, 7991 Friedrichshafen-Fischbach, Germany Filed June 19, 1967, Ser. No. 647,139 U.S. Cl. 103-221 8 Claims Int. Cl. F04b 21/00, 19/22 ABSTRACT OF THE DISCLOSURE A high pressure pump for a sprayer having a run-01f duct within the pump housing connected to a leak-off collecting cross-bore and a pressure regulating valve outlet. The run-olf-duct is lined with a detachable liner. The pump cylinder is lined by spaced adhesively fastened sleeves. The space between the sleeves is joined to the cross-bore thus facilitating the collection of leak-off liquid.

Background of the invention This invention relates to improvements in airless sprayers such as paint sprayers. More particularly it relates to a high pressure pump for such sprayers which features an efficient collection and draining of leak-off liquid accumulating in the pump. This is important because paint especially has the property to cause parts in high pressure pumps to stick and seize, leading to operating trouble. Moreover, the paint may also build up as a crust at points which are not easily accessible for cleaning.

Summary of the invention To overcome the above stated problems the invention contemplates a vertical continuous run-01f duct, fitted inside the pump casing immediately next to the pump cylinder and leading to the spraying medium container. This duct is lined by a cross-bore to the leakage points of the pump cylinder. Further, the pressure regulating valve of the pump also terminates in this duct. By this combination, leak-off liquid is led by the shortest route into the vertical duct, while the venting liquid jet entering the duct from the pressure regulating valve constantly flushes the channel, thus greatly impeding the formation of sticky deposits or clogging of the duct. To permit removal of these harmful deposits from the duct from time to time, the invention includes a linear sleeve for the vertical duct which is preferably made of a plastic material. This liner is provided with openings to match the cross bore and the pressure regulating valve to permit entry of leak-01f liquid, and is detachably fitted into the duct. This liner is normally preferably held on the duct wall by a locating rim and can be taken out and cleaned as required, or if necessary, can be replaced by a new liner sleeve because of the low cost involved.

To prevent any leak-off liquid from emerging around the pump piston section which projects from the cylinder, the invention further contemplates a two-piece cylinder, a liner of split design consisting of two separate liners fitted in spaced relation with axial clearance in the pump housing. In this manner an intermediate space is formed which contains the cross-bore through which the leak-off liquid is carried. Thus the liquid does not have the opportunity to reach the top exit bore of the piston.

The invention also includes having the cylinder liners bonded by adhesive to the housing bore, rather than being press fitted, so that no deformation-of the cylinder bore can occur when the liner is fitted. This avoids the need for retouching work.

The invention further includes a diaphragm partition to separate the tapped bore for the control screw of the valve from the run-off duct which prevents any fouling by paint and sticking of the thread on the control screw 3,430,577 Patented Mar. 4, 1969 of the pressure regulating valve located at the run-off duct, and permits free movement of the needle valve.

Brief description of the drawing Description of the preferred embodiment Pump housing 1 is mounted by its flange 2 to flange 3 of motor 4 which may be arranged, for instance, on cover 5 of the spraying medium container. The pump cylinder is made up of the two cylinder liner sleeves 6 and 7, adhesive-bonded into housing 1, with an axial clearance to form intermediate space 8, into which runs a cross-bore 9. This bore leads to a vertical draining duct 10 for the leak-off liquid running through pump housing 1 and fitted with a plastic liner 11 sleeve. In the example, the liner is fixed by a retaining screw 13 screwed into the blind bore end for making cross-bore 9. The lower extension 12 of the liner leads through an opening in cover 5 into the container.

Pump piston 14 is set into reciprocating motion by cam 15 and piston spring 16, so that the spraying medium is drawn up through line 17 and delivered to the spray gun via line 18. Pump valve 19 with valve spring 20 is located below the piston.

Socket 22 on pump housing 1 accommodates pressure regulating valve 23 with control screw 24, spring 25 and valve needle 26. The latter is led through run-off duct 10 and closes off control bore 27 leading to the pressure side chamber. Fitted into the tapped bore for control screw 24 is a diaphragm 29, fixed to the wall of the bore and to the stem of valve needle 26, which protects the fine thread of the control screw setting spraying pressure against any contact with the spraying medium in duct 10.

In the arrangement shown, the leak-off liquid emerging at the top rim of cylinder liner sleeve 7 into space 8 is led via bore 9 into run-off duct 10, so that the area around top liner sleeve 6 and piston spring 16 remains clean. This also makes it possible to keep the upper opening of duct 10 closed. Since the liquid flowing from control bore 27 is also led into duct 10, this is continuously flushed to some extent, thus reducing the danger of duct 10 becoming clogged. From time to time, it may be advisable to remove and clean plastic liner sleeve 12 or replace it by a new one.

I claim:

1. In a high pressure piston pump for airless spraying wherein the piston is contained within a cylinder within a pump housing through which at least a portion of the spraying medium is conveyed in continuous circulation and said piston acts as a control gate, the improvement comprising:

(a) a vertical run-ofi? duct contained within said pump housing adjacent said cylinder, said duct,

(1) extending to a spraying medium container for draining away leak-off liquid of said spraying 60 medium,

(2) being linked by a cross-bore to selected leakage points of said cylinder, (3) containing an outlet opening of a pressure regulating valve joined to said housing.

2. A combination according to claim 1 wherein said run-off duct is lined with a detachable sleeve, said sleeve (a) containing bores at said cross-bore and pressure regulating valve for permitting the ingress of said leak-off liquid,

(b) being composed primarily of a synthetic elastomer.

3. A combination according to claim 1 wherein said cylinder contains a liner in the form of two separate spaced sleeves with suflicient intermediate clearance for the reception of a terminating end of said cross-bore other than the end at said run-off duct.

4. A combination according to claim 3 wherein said liner sleeves are adhesively bonded to the walls of said cylinder.

5. A combination according to claim 4 wherein said pressure regulating valve has a needle valve at said outlet opening and contains a control screw operable within a tapped bore which is separated from said run-01f duct and needle valve and thus permits free movement of said needle valve.

-6. A combination according to claim 2 wherein said cylinder contains a liner in the form of two separate spaced sleeves with sufiicient intermediate clearance for the reception of a terminating end of said cross-bore other than the end at said run-off duct.

7. A combination according to claim 6 wherein said valve.

References Cited UNITED STATES PATENTS 6/1964 Urso lO3-l53 XR 3/1967 Rosselli 103153 XR ROBERT M. WALKER, Primary Examiner.

US. Cl. X.R. 103153 

